The silver halide-using photography is superior in photographic characteristics, e.g., sensitivity, facility of gradient control, etc., to other photographies such as electrophotography, diazo photography and so on. Therefore, it has so far been employed most prevailingly. In recent years, there has been developed a technique which enables simple and rapid formation of image by changing the image-forming processing of the silver halide-using photography from a conventional wet process using a developing solution or the like into a dry-process by heating or like means.
Heat developable light-sensitive materials are well-known in the field of photographic art, and such materials and the processes therefor are described in, e.g., Shashin Kogaku no Kiso, pp. 553-555, Corona Company (1979); Eizo Joho, p. 40 (April 1978); Nebletts Handbook of photography and Reprography, 7th Ed., pp. 32-33, Van Nostrand Reinhold Company; U.S. Pat. Nos. 3,152,904; 3,301,678; 3,392,020 and 3,457,075: British Pat. Nos. 1,131,108 and 1,167,777: and Research Disclosure, pp. 9-15 (RD-17029) (June 1978).
Many methods for obtaining color images under a dry condition have been proposed. As for the method of forming color images by binding oxidation products of developing agents to couplers, p-phenylenediamine type of reducing agents and phenolic or active methylene-containing couplers are proposed in U.S. Pat. No. 3,531,286; p-aminophenol type of reducing agents in U.S. Pat. No. 3,761,270; sulfonamidophenol type reducing agents in Belgian Pat. No. 802,519 and Research Disclosure, pp. 31-32 (September 1975); and combinations of reducing agents of sulfonamidophenyl type with 4-equivalent couplers in U.S. Pat. No. 4,021,240.
However, the above-described method suffers from the defect that it provides turbid color image, because in such a method both reduced silver image and color image are coextensively produced in optically exposed areas after heat development. As the process for obviating this defect, one which involves the removal of silver image by a liquid treatment, and one which involves the transfer of dye along into another layer, e.g., an image-receiving layer, are considered employable. However, the latter technique has the defect that it is not easy to differentiate between dyes and substances which have not yet undergone the reaction, and to transfer only the dyes.
Another method which comprises introducing a nitrogen-containing heterocyclyl group into a dye, forming a silver salt of the dye, and releasing the dye from the silver salt by heat development is described in Research Disclosure, pp. 54-58 (RD-16966) (May, 1978). This method is unsuitable for common use because it is difficult to inhibit the release of the dye in the unexposed part and therefore, clear image can not be obtained.
A further method which comprises the formation of positive color image using the heat-sensitive silver dye bleach process is described with regard to useful dyes and bleach processes in, e.g., Research Disclosure, pp. 30-32 (RD-14433) (April 1976); ibid., pp. 14-15 (RD-15227) (December 1976); U.S. Pat. No. 4,235,957; and so on.
However, the above-described method suffers from the disadvantage that it requires extra step and material for accelerating the bleach of dyes, specifically superposition of an activator sheet upon a heat developable light-sensitive material, heating thereof and so on, and has the defect that the color image obtained is gradually recuded and bleached with the liberated silver, which is coextensive therewith, upon long time storage.
A still another method which comprises the formation of color image by taking advantage of leuco dyes is described in, e.g., U.S. Pat. Nos. 3,985,565 and 4,022,617. However, this method has the defect that it is difficult to incorporate stably leuco dyes in photographic materials and consequently, the photographic materials are gradually stained upon storage.
For the purpose of solving the above-described problems inherent in conventional methods, the present applicants have already proposed a novel light-sensitive material and a novel image-forming method for using such a material (in European Patent Application (OPI) No. 76,492). The above-described light-sensitive material has the property that it can release a mobile hydrophilic dye by receiving a simple treatment of being heated in a substantially water-free condition, and the above-described method is characterized by the transfer of the mobile hydrophilic dye released from the above-described material into a dye-fixing layer mainly in the presence of a solvent.
As a result of further researches for the above-described invention, it has been found that a mobile hydrophilic dye formed in an imagewise pattern by heating under a substantially water-free condition can be readily transferred into a dye-fixing layer by heating without supplying any solvents at all from the outside, and that it is important for heightening image density and at the same time, for effecting improvement in image sharpness, to incorporate into a dye-fixing material such a compound as to react with or to adsorb a silver halide, thus achieving the present invention.
Since the present invention involves the transfer of the dye present in a light-sensitive material into a separate dye-fixing material, a special contrivance is required of the present invention in order to give excellent qualities to the final image fixed to the dye-fixing material. That is, it becomes necessary to prevent the increase in fog density due to needless progress of development in the transfer step for the purpose of improving the qualities of dye image transferred into the dye-fixing layer.